require

require(...) loads the specified JavaScript or JSON file, allowing to split your configuration across multiple files.
If the supplied path string ends with .js, the file is interpreted as JavaScript code, almost as though its contents had been included in the currently-executing file. If the path string ends with .json, require() returns the JSON.parse() of the file's contents.
If the path string begins with a ., it is interpreted relative to the currently-loading file (which may not be the file where the require() statement is, if called within a function), otherwise it is interpreted relative to the program's working directory at the time of the call.
dnsconfig.js
require("kubernetes/clusters.js");
​
D("mydomain.net", REG_MY_PROVIDER, PROVIDER,
IncludeKubernetes()
);
kubernetes/clusters.js
require("./clusters/prod.js");
require("./clusters/dev.js");
​
function IncludeKubernetes() {
return [includeK8Sprod(), includeK8Sdev()];
}
kubernetes/clusters/prod.js
function includeK8Sprod() {
return [
// ...
];
}
kubernetes/clusters/dev.js
function includeK8Sdev() {
return [
// ...
];
}
You can also use it to require JSON files and initialize variables with it:
dnsconfig.js
var domains = require("./domain-ip-map.json")
​
for (var domain in domains) {
D(domain, REG_MY_PROVIDER, PROVIDER,
A("@", domains[domain])
);
}
domain-ip-map.json
{
"mydomain.net": "1.1.1.1",
"myotherdomain.org": "5.5.5.5"
}

Future

It might be better to rename the function to something like include() instead, (leaving require as a deprecated alias) because by analogy it is much closer to PHP's include() function than it is to node's require(). After all, the reason node.js calls it "require" is because it's a declarative statement saying the file is needed, and so should be loaded if it hasn't already been loaded.
In contrast, DNSControl's require() is actually an imperative command to load the file and execute the code or parse the data from it. (So if two files both require("./tools.js"), for example, then it will be loaded twice, whereas in node.js it would only be loaded once.)